There are many types of pallets, which are used throughout the world to facilitate shipment and transportation of goods. The purpose of the pallet is to provide support for cargo particularly during shipment and storage. There has been an increasing requirement for such pallets to become more sophisticated due to varying standards and demands. Pallets can be formed from timber (i.e., wood), but these pallets suffer from several disadvantages because of the inherent characteristics of wood. For example, wooden pallets are naturally heavy, bulky, and can be expensive because of the nature of the material used in their construction. In addition, wooden pallets suffer deterioration due to inclement weather conditions and can suffer damage from water that may be present in the location in which the pallets are being used.
The presence of water can result in decomposition of the wood and resultant weakening of the structure of the pallet. Furthermore, wooden pallets are generally held together with the use of glue, adhesives, and/or metal nails or staples. These fixation methods can also suffer as a result of the inclement conditions the pallet may be subjected to and are manifested by deterioration of the adhesive and/or corrosion of the nails or staples. Wooden pallets can also be subjected to insect infestation, which can also result in deterioration of the pallet and can transmit undesirable insect infestations from one location to another. Many countries (e.g., United States, Australia, Canada, New Zealand, and China) require wooden pallets to be certified pest free, which means that the pallets have to undergo a process, e.g., heat treatment or fumigation, in order to be certified pest free.
Plastic pallets can be used as an alternative to wooden pallets, due to their moisture resistance, toughness, and flexibility in design through injection molding, structural foam, and extrusion/thermoforming processes not available in wooden pallets. However there can be concerns regarding the fire properties of plastic pallets. With fire control infrastructure (e.g., sprinkler systems) designed around wooden pallets, a challenge arises to ensure plastic pallets perform satisfactorily to meet the large-scale burn standards, e.g., UL 2335 (Second Edition, Jul. 28, 2010). Without the proper pallet design and construction materials, plastic pallets could fail due to molten plastic flow during fires, spreading burning material, and could generate levels of heat beyond their wooden counterparts, resulting in conditions that can overwhelm sprinkler systems' ability to control a fire. Because of these risks, the use and storage of plastic pallets which do not meet large-scale burn standards can be challenging. A desired feature of pallets is that the pallets do not spread flames from one pallet to another in the case of a fire during use or storage of the pallets. The use of flame retardant additives compounded into a plastic resin has been the primary solution to retarding flame spread and fire growth, but the drawbacks can be considerable, including loss of material mechanical properties, loss of toughness, and environmentally unfriendly flame retardant additive systems (for example, non-restriction on hazardous substances (ROHS) compliant Halogen additives) Thus, there is a need for environmentally friendly pallets with flame retarding and resisting properties and also a continual need for an improvement in the design and use of plastic pallets.